In a variety of subsea well applications, a blowout preventer is positioned at a subsea well. Once positioned, the blowout preventer is able to receive many types of subsea equipment, such as a subsea test tree, tubing hanger running tool, and downhole completion equipment. Components of the subsea equipment are controlled via electrohydraulic controls located in a module above the subsea test tree. A dedicated hydraulic control line is used for each operating tool function, and thus a relatively large number of hydraulic control lines, e.g. 20-26 or more, may be routed from the module to the corresponding tool or component. Running this number of control lines can be extremely costly due to the use of hoses, hydraulic lines, and gun drilling through various parts to form the independent hydraulic control conduits.
The hydraulic control lines also may be routed over substantial lengths between the module and the component being hydraulically controlled. As a result, the response times can be slowed. In many applications, the subsea test tree includes a failsafe valve which is operated hydraulically and should be able to close as rapidly as possible in an emergency situation. The relatively long hydraulic control lines cause the control fluid to pass through an extensive flow path to pressurize the close control piston and to vent the open control piston of the failsafe valve, thus slowing the response time of the valve. The long hydraulic control lines also can be crimped during an emergency shearing operation, thus preventing venting of the pressure to enable closure of the failsafe valve.